Wednesday, November 2, 2011

Re-setting the panel level

I've been agonizing over finding the correct level setting for the Aragon which drives my acoustats. I could have just used the level I had been using for the Parasound (+0.4 dB) adjusted upwards for reduced amp gain of the Aragon (+1.5dB) except I had been attenuating the Parasound by some unrecorded level, and I made the big mistake of twiddling the Parasound gain adjust knobs to maximum for frequency response testing before testing their previously set level.

Yesterday I had figured I set the Parasound gain to somewhere between -6 and -12dB. I figured I wouldn't have done 6dB, because I know that is a maximum series resistance condition. So 12dB? That sounded too high. I was beginning to think I had used 10dB. But that's an odd one, the infinite repeating decimal of 3.33. I wouldn't have done that, would I?

Meanwhile, I was listening to various music, and readjusting the level to suit each one. Last night I decided Hotel California didn't sound clear enough in the mids, so I increased the level from 6.9 to 6.5 (neither of which made much sense thinking about how I might have attenuated the Parasound, so I worried about that.)

For 6dB previous attenuation level on the Parasound, the new level would be 4.1dB. (I tried that for awhile but thought it too thin.)

For 9dB attenuation, the new level would be 7.1dB (close to the 6.9dB level I had been using for Imaginary Day).

For 12dB attenuation, the new level would be 10.1dB. Thinking I might have chosen 10dB attenuation (despite the numerical difficulty), I listened to Fleetwood Mac Rumours DVD-Audio (which sounded better than I'd ever heard it) at 8.1dB.

Mind you in making these adjustments what I'm really doing is setting the relative bass level, because that is saying constant. At present, the supertweeter is not connected (and its level hardly matters anyway). The subs cross over at 85 Hz. There is no simple way to set sub level, the response below 300 is highly muddled due to room modes and there are peaks and dips as large as 20dB, so you can't just set a matching level at some particular frequency or pair of frequencies.

Of course, there's no guarantee that I set the level of the Parasound correctly, it's just that over time you readjust until it's about right and sooner or later forget to make any further adjustments until something like this happens.

The last thing I listened to last night was the Rebecca Pidgin Spanish Harlem track with acoustic bass. A famous mastering engineer said he always used that to set bass levels; you want the acoustic bass notes equal in level. At the 6.5dB level I had gravitated toward, the third (highest) bass note sounded too loud, way too loud. So then I dialed in 8.1, which sounded considerably more natural. Of course I may also be fighting room nodes at the high bass note, I have often noticed it sounds loudest in the living room, so this is hardly a perfect test. Also, the third note sounds like an open string, which inherently sounds louder and different. But I didn't think it should sound like what I heard at 6.5.

Now this morning I thought I'd go back through this website and find out if I had ever recorded the Parasound attenuation level. I had set it when experimenting with attenuating all amplifiers to reduce noise from the Behringer, which was most noticeable on the supertweeter but measureable elsewhere.

Indeed, after experimenting with 3dB Harrison Labs attenuator, which I thought made the midrange sound funny due to excess loading on the Behringer, I ultimately set the level via the Parasound level controls to 6dB, and that now seems to be the last and only documented case of setting the Behringer level control. At the time, I opined that 9dB would be the max level for attenuation, to keep the Behringer from getting into its more distorted upper output level range.

So now it appears that if I wanted to duplicate the previous situation exactly, I'd now set the level to -4.1. But that sounds thin, and I may like 8.1 better. Effectively, I'm adding 4dB boost to the subs compared to previously.